An electro-fluorescence device is a device which may switch fluorescence off and on by the oxidation and reduction of an electro-active material which is introduced into the device by the applied voltage. The characteristics of the electro-fluorescence device are that an electro activator receives energy at an excited energy level of a fluorescence material, thereby leading to a fluorescence extinction or shift of the wavelength, and that it is possible to control the reception of energy from the fluorescence material according to the oxidation and reduction of the electro activator. The electro-fluorescence device may be largely classified into a type in which an electro-active part is included in the fluorescence material, and a type in which a fluorescence material and an electro-active material are each included in the device.
As a technology in the related art, there was a device in which electro-fluorescence characteristics are implemented by singly using an aromatic compound including anthracene, biphenyl ether, biphenyl alkylene, biphenyl sulfide, naphthalene, pyrene, perylene, pentacene, tetrazine and derivatives thereof, a triazine-based compound, and a triazineoxyphenyl-based compound, or additionally using an electro-active material such as ferrocene, benzoquinone, and iodide.
In particular, electro-active fluorescence monomers and polymers may have a stable energy transfer structure without limitation in concentration, and implement various fluorescence colors through molecular structure design, so that studies for these monomers and polymers as a fluorescence display device and a functional bioimaging material have been actively conducted.
For the application to the functional bioimaging and fluorescence display device, studies of controlling the fluorescence intensity at various wavelength ranges have been conducted, and materials with various wavelength regions such as, for example, a polyoxadiazole-based polymer (335 nm, blue fluorescence), a tetrazine-based compound (558 nm, yellow fluorescence), a quantum dot (600 nm, red fluorescence) have been studied, but most of the studies implement the control of fluorescence with a visible light region, and a device which controls the wavelength with an infrared region range has never been suggested.
Light at an infrared region has good tissue penetration and is generally innocuous to cells, and thus has been actively applied in bioengineering such as bioimaging, and a photothermal therapy. In the case of Korean Patent Application Laid-Open Nos. 10-2011-0057837 and 10-2012-0069914, light at the infrared region has been applied in order to complement information which may be obtained with the visible light in a night vision enhancement device and a thermal imaging camera.
In the case of an organic material, fluorescence at the infrared region is observed from an organic compound, such as cyanine-, squaraine-, and porphyrin-based compounds, in which a conjugated structure is longitudinally connected, and in the case of an inorganic material, fluorescence at the infrared region is observed from a quantum dot formed of PbS and PbSe and an Er-based metal complex, and is actively applied as bioimaging.
As a method of controlling an infrared light emitting signal in the related art, there was a method of injecting a fluorescence extinguisher derivative such as an active oxygen species in the process of delivering energy to a fluorescence material in the bioimaging, and in the case of injecting a fluorescence extinguisher derivative, the fluorescence extinguisher derivative is suitable as a one-time sensing, but it is difficult to use the derivative several times. As a device for electrically generating an infrared signal, an infrared LED and OLED may be used, but this device is an electro light-emitting device, and thus has high driving voltage and power consumption.